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Small Ponds (small + pond)
Selected AbstractsSmall ponds and big landscapes: the challenge of invertebrate spatial and temporal dynamics for European pond conservationAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2005Michael Jeffries Abstract 1.Present understanding of the ecology and conservation of European ponds is built upon two traditions: first, extensive surveys of many ponds, often based on one visit and second, intensive experiments usually restricted to one site but over longer periods. Neither approach adequately captures the long-term spatial and temporal dynamics of pond invertebrates. 2.Over the last decade the significance of landscape, land use and species turnover between ponds has been highlighted both for the conservation of pond wildlife and as a key factor in the ecology of pond invertebrates. These large-scale spatial patterns and the resulting heterogeneity of ponds and their wildlife are not effectively addressed by the tradition of intensive, single-site experiments. Longer-term databases, sufficient to allow analysis of species turnover, show considerable annual temporal variation in species' distributions, a phenomenon not adequately addressed by extensive, single-year surveys. 3.The limited number of studies that combine landscape spatial scale with inter-annual time scales all suggest that important invertebrate dynamics occur at these levels. Species and metacommunities show spatial variation and inter-annual turnover. Data from a 10-year study of small, experimental ponds show temporal and spatial variation in species distributions and community measures responding to scales from the individual pond up to long-term climate trends, e.g. the North Atlantic Oscillation. 4.The ecological integrity of ponds requires the conservation of this potential for variation, change and heterogeneity. Copyright © 2005 John Wiley & Sons, Ltd. [source] Growth and ageing of feral Xenopus laevis (Daudin) in South Wales, U.K.JOURNAL OF ZOOLOGY, Issue 4 2001G. J. Measey Abstract A feral population of African clawed frogs Xenopus laevis from a small pond in South Wales was sampled continuously for 2 years to assess morphometric growth. Toe-clips taken at intervals over a 4-year period were found to contain lines of arrested growth (LAG) which corresponded to each consecutive winter. The first toe-clips revealed a population structure within the pond consisting of a dominant cohort of frogs with one LAG that metamorphosed in 1993, and a few older individuals. Subsequent toe-clips in 1996 and 1998 gave two and four more LAG, respectively. Morphometric growth was found to be restricted to a short growing season, significant differences in the growth rates of males and females being first detected in their third growth season. Reproductively active frogs were still within their initial period of growth, suggesting that Xenopus laevis does not conform to the standard energy resource allocation mechanisms of typical ectotherms. [source] Variability of dry sediment bulk density between and within retention ponds and its impact on the calculation of sediment yieldsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2001Gert Verstraeten Abstract Monitoring sediment yields from catchments is important for assessing overall denudation rates and the impact of environmental change. One of the methods used to assess sediment yield is by quantifying sedimentation rates in reservoirs, lakes or small ponds. Before reliable sediment yield values (t ha,1 a,1) can be computed from such sedimentation records, the measured sediment volumes need to be converted to sediment masses using representative values of the dry sediment bulk density. In textbooks, simple relations predicting dry sediment bulk density from sediment texture, time since deposition and hydrologic condition are presented. In this study, 13 small flood retention ponds in central Belgium were sampled to reveal the variability in dry sediment bulk density and to test the commonly used relations to predict dry sediment bulk density. Dry sediment bulk density varies not only between the selected ponds (0·78,1·35 t,m,3) but also within individual ponds (coefficient of variation at 95 per cent ranges from 7 to 80 per cent). The observed variability can be attributed primarily to the hydrologic condition of the retention pond and, also, to sediment texture. The existing relations are not a reliable predictor for the observed dry bulk densities, because they are primarily based on sediment texture. Thus, when using volumetric sedimentation data from small ponds with varying hydrologic condition to predict sediment yield, existing relations predicting dry sediment bulk density cannot be applied. Instead, frequent and dense sampling of sediments is necessary to calculate a representative value of the dry sediment bulk density. Copyright © 2001 John Wiley & Sons, Ltd. [source] A TADPOLE-INDUCED POLYPHENISM IN THE SALAMANDER HYNOBIUS RETARDATUSEVOLUTION, Issue 10 2002Hirofumi Michimae Abstract., Larvae of the salamander Hynobius retardatus have two distinct morphs: normal and broad-headed, cannibal morphs. We performed three experiments to differentiate among the following hypotheses: The broad-headed morph is induced to allow: (1) feeding on nutritious conspecifics; (2) exclusion of strong competitors for food or space; or (3) feeding on large, tough prey when smaller prey items are unavailable. When newly hatched larvae were reared with a heterospecific, Rana pirica (an anuran amphibian) tadpoles, the broad-headed morph was induced more frequently compared with those reared with conspecifics. The phenotype expressed depended on the size of the tadpoles: The broad-headed morph occurred more frequently with small and the normal morph with large tadpoles. Metamorphosis occurred sooner in larvae fed conspecifics compared with those fed heterospecific tadpoles, and the mean growth rate of larvae fed conspecifics was significantly faster than that of those fed tadpoles, suggesting that the heterospecific tadpoles were less nutritive than the conspecifics. These results do not support the hypotheses that the broad-headed morph evolved for consuming conspecifics because of their better balance of nutrients or for excluding strong competitors for food or space. We tentatively conclude that the morph evolved to eat large, tough prey, including both conspecifics and heterospecific tadpoles. Because H. retardatus usually spawns very early in the spring in small ponds partially covered with ice and snow, newly hatched larvae may starve from the lack of proper food owing to extremely low water temperatures. Thus, the broad-headed morph of H. retardatus may represent a cold-habitat adaptation to overcome the severe circumstance when the only food items available are relatively large conspecifics or heterospecific tadpoles. [source] Reconstructing floodplain sedimentation rates from heavy metal profiles by inverse modellingHYDROLOGICAL PROCESSES, Issue 1 2002Dr Hans Middelkoop Abstract The embanked floodplains of the lower River Rhine in the Netherlands contain large amounts of heavy metals, which is a result of many years deposition of contaminated overbank sediments. Depending on local sedimentation rates and changing pollution trends in the past, the metal pollution varies greatly between different floodplain sections as well as vertically within the floodplain soil profiles. Maximum metal concentrations in floodplain soils vary from 30 to 130 mg/kg for Cu, from 70 to 490 mg/kg for Pb and from 170 to 1450 mg/kg for Zn. In the present study these metals were used as a tracer to reconstruct sedimentation rates at 28 sites on the lower River Rhine floodplains. The temporal trend in pollution of the lower River Rhine over the past 150 years was reconstructed on the basis of metal concentrations in sediments from small ponds within the floodplain area. Using a one-dimensional sedimentation model, average sedimentation rates over the past century were determined using an inverse modelling calibration procedure. The advantage of this method is that it uses information over an entire profile, it requires only a limited number of samples, it accounts for post-depositional redistribution of the metals, and it provides quantitative estimates of the precision of the sedimentation rates obtained. Estimated sedimentation rates vary between about 0·2 mm/year and 15 mm/year. The lowest metal concentrations are found in the distal parts of floodplain sections with low flooding frequencies and where average sedimentation rates have been less than about 5 mm/year. The largest metal accumulations occur in low-lying floodplain sections where average sedimentation rates have been more than 10 mm/year. Copyright © 2002 John Wiley & Sons, Ltd. [source] Behavioural syndromes differ predictably between 12 populations of three-spined sticklebackJOURNAL OF ANIMAL ECOLOGY, Issue 6 2007NIELS J. DINGEMANSE Summary 1Animals often differ in suites of correlated behaviours, comparable with how humans differ in personality. Constraints on the architecture of behaviour have been invoked to explain why such ,behavioural syndromes' exist. From an adaptationist viewpoint, however, behavioural syndromes should evolve only in those populations where natural selection has favoured such trait covariance, and they should therefore exist only in particular types of population. 2A comparative approach was used to examine this prediction of the adaptive hypothesis. We measured behavioural correlations in 12 different populations of three-spined stickleback (Gasterosteus aculeatus) and assessed whether they indeed varied consistently according to the selective environment, where population was unit of analysis. 3For a sample of fry from each population, we measured five different behaviours within the categories of (i) aggression (towards conspecifics); (ii) general activity; and (iii) exploration,avoidance (of novel foods, novel environments and altered environments). 4We show that behavioural syndromes are not always the same in different types of stickleback population: the often-documented syndrome between aggressiveness, activity and exploratory behaviour existed only in large ponds where piscivorous predators were present. In small ponds where predators were absent, these behaviours were not (or only weakly) associated. 5Our findings imply that population variation in behavioural syndromes does not result from stochastic evolutionary processes, but may result instead from adaptive evolution of behaviour favouring what should prove to be optimal trait combinations. [source] Phenotypic plasticity of anuran larvae: environmental variables influence body shape and oral morphology in Rana temporaria tadpolesJOURNAL OF ZOOLOGY, Issue 2 2002Miguel Vences Abstract Environmental variables shaped the morphology of tadpoles of the common frog, Rana temporaria, in various ways at the Pyrenean locality Circo de Piedrafita. Examining only specimens in similar developmental stages, those from small ponds (with higher temperature and higher tadpole density) had lower growth rates, lower relative tail height, lower relative body width and fewer labial keratodonts and keratodont rows. The variation in keratodonts may have been caused by heterochrony related to the slower growth rate. The number of lingual papillae also differed between ponds but was not related to pond size. Higher predator densities caused a higher percentage of damaged tails and a lower relative tail length in specimens with apparently intact tails, probably as a result of incomplete regeneration after mutilations earlier in development. [source] Growth and reproduction of threatened native crucian carp Carassius carassius in small ponds of Epping Forest, south-east EnglandAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2010Ali Serhan Tarkan No abstract is available for this article. [source] Growth and reproduction of threatened native crucian carp Carassius carassius in small ponds of Epping Forest, south-east EnglandAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009Ali Serhan Tarkan Abstract 1.The crucian carp Carassius carassius is a species of cyprinid fish native to south-east England, but few studies exist on its growth and reproduction in England, and the species is threatened by introductions of its Asiatic congener, goldfish Carassius auratus. To increase knowledge of the crucian carp as a means of aiding its conservation, the present study assesses the growth (back-calculated length at age, body condition) and reproduction (fecundity, egg size, length and age at maturity) of crucian carp in small ponds of Epping Forest (north-east London, England). 2.Evaluation of growth and reproduction data with published data for populations from northern Europe (i.e. latitude ,50°) suggest that growth is very variable, even within the same area, and that data on reproductive indices, in particular length and age at maturity, are scarce. In England, the length at age trajectory of crucian carp living in sympatry with feral goldfish Carassius auratus did not differ significantly from allopatric crucian carp populations, but crucian carp body condition and relative fecundity (eggs per body weight) were highest, and mean age and standard length at maturity were lowest in sympatry with goldfish. 3.These data suggest that somatic growth and reproductive output may be maximized in crucian carp when confronted by coexistence with feral goldfish. However, the potential impact of goldfish introductions on crucian carp growth and reproduction requires further study, involving a much larger number of crucian carp populations, both in allopatry and sympatry with feral goldfish populations. © Crown copyright 2009. Reproduced with the permission of Her Majesty's stationery Office. Published by John Wiley & Sons, Ltd. [source] | ||||||||||